The present invention generally relates to plastic containers, particularly to plastic containers for containing food products, specifically to plastic containers for containing refrigerated food products and more specifically to plastic containers for containing yogurt and especially custard.
One area where the use of plastic containers has become widespread is in the food packaging industry. Accordingly, it is common for these plastic food containers to serve as the end display package in which the food product is presented for sale to the consumer. One such plastic container which has gained wide market acceptance for refrigerated food products, especially yogurt, custard and the like, is sealed by a thin, flexible, foil seal member extending over the top of the container. Such containers can be thermo-formed or blow molded, but because of the clear advantages have been recently formed by injection molding for certain container shapes.
It can be appreciated that if not sealed properly, communication is allowed between the interior of the containers and the atmosphere, with containers allowing communication known in the industry as leakers. Such improper sealing results in the food product becoming moldy, especially within the normal or desired shelf life of the product. As such mold normally cannot be detected until the foil seal member is removed, consumers are normally the first to determine that the seal is defective when the container is opened to consume the food product. Thus, consumer complaints are a normal consequence.
In normal production, containers are filled and seal members are sealed to the filled containers at the rate in the order of 400 per minute. At these rates, alignment of the container with the sealing plattens and other operational factors become significant in obtaining proper sealing of the containers. The particular sealing lip of the container is also another factor in obtaining proper sealing of the containers. In particular, unsupported sealing lips extending radially inward of the container sidewall which are utilized in containers having large diameter bases and small diameter tops are especially prone to deflecting under the pressure of the sealing plattens. Also, the particular food product being filled in the containers and specifically contamination of the sealing lips by the food product can cause problems in sealing of the containers. Prior to the present invention, as much as 5 to 20 percent of the injection-molded, polypropylene containers having radially inwardly extending, unsupported sealing lips for holding custard were improperly sealed or in other words were leakers.
Thus, a need exists for plastic containers which are not as prone to leaking when sealed utilizing conventional sealing mechanisms and which otherwise overcomes the deficiencies of prior plastic containers for food products, especially of the type having radially inwardly extending, unsupported sealing lips.
The present invention solves this need and other problems in the field of plastic containers for food products by providing, in the preferred form, an improved sealing lip projecting inward from the top of the sidewall of an upper container portion of a plastic container. Specifically, the lip includes outer and inner annular portions, with the outer face of the outer annular portion extending upward away from the hollow interior while the outer face of the inner annular portion extends downward towards the hollow interior. The upper surface of the lip including the outer faces of the outer and inner annular portions is continuous, smooth and free of steps and ridges to present a continuous seal area for a thin, flexible, foil seal member independent of the deflection of the lip into the interior of the container.
It is thus an object of the present invention to provide a novel plastic container for food products.
It is further an object of the present invention to provide such a novel plastic container especially adapted for refrigerated food products.
It is further an object of the present invention to provide such a novel plastic container especially adapted for custard.
It is further an object of the present invention to provide such a novel plastic container including an improved seal lip.
It is further an object of the present invention to provide such a novel plastic container including an unsupported, improved sealing lip.
It is further an object of the present invention to provide such a novel plastic container including a radially inwardly extending, improved sealing lip.
It is further an object of the present invention to provide such a novel plastic container reducing the incident of improper sealing.
It is further an object of the present invention to provide such a novel plastic container especially adapted for injection molding.
It is further an object of the present invention to provide such a novel plastic container providing a continuous seal area for a thin, flexible, foil seal member independent of the deflection of the sealing lip into the interior of the container by the sealing mechanism.
These and other objects and advantages of the present invention will become clearer in light of the following detailed description of an illustrative embodiment of this invention described in connection with the drawings.